Apparatus for attenuating glass fibers



Nov. 27, 1962 D. LABINO APPARATUS FOR ATTENUATING GLASS FIBERS Filed May 3, 1960 INVENTOR. DOMINICK LAB NO Q6/7 17 ATTORNEY The present invention relates generally to the attenuation of fine glass fibers from primary glass filaments, and more particularly to an improved apparatus for maintaining the primary filaments in alignment during the attenuating thereof.

In one method of producing fiame attenuated glass fibers, a glass is melted within a crucible having a bottom wall provided with a plurality of orifices through which the molten glass is exuded and drawin downwardly in the form of primary filaments. A number of these primary filaments are simultaneously drawn from the cruci- =ble and fed transversely into a high temperature, high velocity gaseous blast which melts the ends of the primary filaments and the force of the blast attenuates the melted ends into relatively fine diameter fibers. This process is generally disclosed in US. Patent No. 2,489,243, issued November 22, 1949, to C. J. Stalego.

It has been found that about twenty to twentytw primary filaments may be attenuated per lineal inch of burner blast and still provide sufficient room between adjacent filaments so that all surface portions thereof are exposed to an adequate volume-of blast constituents. It is very important that the proper spacing be maintained so that :a'given pair of filaments are not in contact with one another when subjected to the attenuating blast. When this occurs, the filaments are not properly heated and small globules of glass are formed.

In order to maintain the primary filaments in spaced relation from one another it is known to feed them endwise into a confining guide device of the type shown in the Stalegopatent. Such guides, however, have not been entirely satisfactory in that when a primary filament breaks, which quite often happens, it is necessary to rethread the filament into the guide. Also, a certain amount of frictional resistance is presented to the filaments as they move downwardly in the guide thus placing them in compression and increasing the likelihood of breakage.

One means of solving this problem has been to use, as a combination guide and back up member to enable the filaments to resist the attenuating blast, a threaded rod which is positioned beneath the primary attenuating means which is usually in the form of rollers as shown in the Stalego patent. Since there is no confining member for the filaments when a threaded rod is used, it is relatively simple to realign a filament after it has been broken. However, in order to obtain maximum production out of a given machine a great many primary filaments are fed across the mouth of the burner. For example, one type of bushing in commercial use feeds 80 or 120 primary filaments in a circular pattern having a. diameter in the order of about 8 or 10 inches. Since the exit slot of the burners commonly used for attenuating the primaries is only in the order of about 4 inches, the primary filaments must be gathered together prior to being fed into the burner blast. Also, the primary filaments must be aligned with one another in substantial parallelism. Since the primary filaments are gathered together there is always-a tendency therefore for them to spring apart from one another and out of the threads of the rod. Furthermore, when initially starting a fiber attenuating production run, as a general rule, the primary filaments pass by the burner exit slot until such time as the burner has been warmed up to operating temperature,

Upon passing the burner the filaments tend to gather in coils thus twisting the primaries out of their original alignment and out of the threads in the rod. This then necessitates the attention of operating personnel to realign the filaments. Also, and as previously pointed out, when a primary filament breaks, it is again necessary to realign the broken filament with the others. The breakage problem occurs more often in the starting operation and is undoubtedly affected by the twisting of the primary filaments resulting from their tendency to coil.

In accordance with the present invention, however, there is provided a novel apparatus for aligning the primary filaments and maintaining these primary filaments in alignment during the attenuation thereof into fine fibers.

It is therefore an important object of the present invention to provide an improved apparatus for attenuating glass fibers.

Another object of the invention is to provide an improved apparatus for maintaining continuous glass filaments in alignment prior to the attenuation thereof into fine glass fibers.

A further object of the invention is to provide apparatus formaintaining the filaments in alignment which requires a minimum or no attention from operating personnel during the attenuating process.

Other objects and advantages will become more apparent inthe-course of the following description.

In the drawings wherein like numerals are employed to designate like parts throughout the same:

FIG. 1 is an elevation view of apparatus for attenuating glass fibers and illustrating the novel alignment maintaining means of the invention;

FIG. 2 is a fragmentary sectional View taken along the line 2--2 of FIG. 1, and showing primary filaments in contact with the alignment maintaining means of the invention;

FIG. 3 is an elevation View of a modified form of the invention; and

FIG. 4 is an enlarged elevation view of a portion of the apparatus of the invention.

The present invention makes use of the tendency of one cylindrical body to straighten when driving a second cylindrical body positioned transversely and at a right angle with respect to the direction of movement of the first body. More specifically, if an elongated cylindrical rod is moved generally axially thereof in a given direction and tangentially engages a freely rotatable cylindrical body having its axis positioned at an angle thereto, there is a tendency for the rod, while in contact with and rotating the cylinder, to orient itself so that its axis is at substantially a angle with the axis of rotation of the cylinder. In accordance with the present invention, advantage is taken of this phenomenon by orienting the axis of rotation of a smooth surfaced rotatable member, preferably a metal roller having a right circular cylindrical configuration and a polished surface, at an angle of 90 to the desired direction of movement of the primary filaments, and supporting the rotatable member freely so that the frictional engagement of its surface with the filaments causes the movable member to rotate in the direction of movement of the primary filaments. Thus any primary filaments which are out of alignment or parallelism are caused by the frictional contact to slip laterally along the surface of the member and return to the desired position relative to the other filaments. More specifically, when a given filament engages the roller at other than an angle of 90 with respect to the axis of the roller, a frictional force component is created which is substantially parallel to the roller axis. Since the roller has a smooth surface, this component is large enough to overcome steady frictional resistance between the filament and the roller and thus cause the filament to slide along the roller until a substantially 90 relationship between the filament and the axis of the roller is attained.

With reference now to the drawings, and particularly to FIG. 1, there is shown fiber attenuating apparatus, generally indicated by the numeral 10, and including a bushing or crucible 11', primary attenuating means 12, the filament aligning means 13, and an attenuating burner 14. The crucible may be formed in a manner and of material well known to the art, for example, of platinum, and is providedwith a plurality of nipples 15 through which the molten glass within the crucible passes and is after-wards drawn into fine primary filaments 16 by the attenuating means 12 which comprises a pair of coacting rollers 17 driven by a suitable source of power (not shown);

Immediately above the rollers there is positioned a transverse rod or bar 18 having its surface provided with a series of relatively closely spaced grooves 19. The bar 18 divides the filaments 16 into two groups and gathers them toward one another to'prirnarily align the filaments in substantial parallelism prior to passing between the attenuating rollers 17. It will be understood, of course, that when only a relatively few primary filaments are drawn, as is the case with the apparatus shown in the aforementioned Stalego patent, such a rod is not necessary.

After passing between the attenuating rolls 17, the primary filaments are fed downwardly in a substantially vertical plane to be contacted by the novel alignment maintaining means of the invention which is generally indicated by the numeral 13, and are thenpassed downwardly into contact with a transversely disposed backup bar 20 which prevents the filaments from being blown away from the burner 14. The burner may be of 'the type disclosed in StalegoPatent No. 2,489,243. However, it will be readily understood that other types of attenuating blasts may be used as long as the temperature and velocity thereof are suflicient to accomplish the intended purpose.

After being attenuated by theburner 14, the fine diameter fibers are carried away from the burner by the force and velocity of the blast emitted therefrom and are collected upon a transversely disposed, movable belt 21 to form a mat 22. If desired, the fibers may be sprayed while they are carried bythe burner blast with a suitable thermosetting binder emitted from nozzles 23 and the binder impregnated mat subsequently passed through an oven to cure the binder and form a bonded mat.

In accordance with the invention the moving primary filaments are caused to tangentially engage and drive a movable member having a smooth curved surface portion such that the points of tangency define a straight line extending transversely at a right angle to the desired path of movement of the filaments. For optimum results the radius of the curvature of the portion of the surface in contact with the filaments should be constant at all points about and along a straight line axis defined by the intersection of a pair of planes, one of, which is parallel to the plane containing the filaments and the other of which is disposed at a 90 angle to the first plane and also to the plane containing the filaments. With such a member being directly driven by the primary filaments, each filament acts:

intersection of. the periphery of the body and a plane passing through the body perpendicular to the axis of revolution preferably should be at an equal distance from the axisof revolution. Thus the body of revolution may be a cylinder of revolution, a cone of revolution, or another body which satisfies the above conditions. I

One type of novel filament alignment maintaining means 13 comprises a right circular cylinder having its axis of rotation oriented so as to locate its surface in tangential contact with the primary filaments. As shown in FIG. 1, preferably a pair of such cylinders 24 and 25 are used and preferably are positioned in such a manner that the longitudinal axis,vor axis of rotation, of each is substantially parallel to the axes of the attenuating rollers 17 and also substantially parallel to one another and contained in parallel, vertically spaced horizontal planes. Thus each roll 24 and 25 also has its longitudinal axis disposed at an angle of to the vertical or, as previously mentioned, at an angle of 90 to the desired direction of travel'of the primary filaments. More specifically, the axis of rotation of each roll is defined by the intersection of a pair of planes, the first of which is spaced from and parallel to the plane containing the filaments and the other of which is disposedat an angle of 90 to the plane containing the filaments. For all practical purposes, however, a deviation in angularity or parallelism of saya degree or so may be tolerated, particularly having in mind the-fact that'the rollers are located in an area of relatively high temperature and thus expansion and contraction under temperature differentials can cause some'warpage in the supporting structure for the apparatus; However, for optimum results it is important'that the pair of planes, the intersection of whichdefines the axis of each of rolls 24 and 25, are spaced from one another at an angle as close to 90 as is possible and that the first plane be as parallel as is possible to'the path of the fila-' ments.

As previously pointed out, the benefits of the invention are achieved by frictionally driving the cylindrical rolls through" tangential contact with the moving primary filaments. Thus the stub shafts 26 provided at each end of thecylindrical rollers are journaled in bearings 27 supported by plates 28 disposed on either side of the burner 14. Preferably, roller'or ball bearings are used so as to maintain the driving frictional force at a minimum since it is desired for the primary filaments to use the minimum possible force necessary in order to rotate the cylinders. I

As shown in FIG.. 1, the axes of the rolls 24 and 25 are located in laterally spaced vertical planes and preferably the spacing of the planes is such that the plane containing the path of the filaments would also contain a portion of the surface of each of the two rolls. Since the primary filaments are generally in the order of about 0.015-0.025 inch in diameter,.this would cause a slight bend in the filaments which tends to maintain them in substantially tangential positive driving contact with the surfaces of both rolls.

In order toallow the primary filaments to shift relative to one another and realigned when necessary as a result of driving the rolls 24and 25, it is important that the surface of the back up bar 20 contacting the filaments be smooth and preferably flat so as to give other than point contact with the filaments. A preferred form of construction for the bar20 is shown in FIG. 4 and provides a fiat, smooth contact surface a which extends for an appreciable distance along the primary filaments 16. In order to provide a substantially frictionless contact surface the bar 20 is preferably formed of carbon or graphite although a highly polishedmetal bar may be used.

A modified form of the invention is shown in FIG. 3 and comprises a pair of rolls 29 and 30 laterally spaced from one another and supporting an endless flexible belt 31 of preferably substantially uniform thickness throughout its length. The axes of the rolls 29 and 30 as was the case with the rolls 24 and 25, are positioned in planes substantially parallel to the vertical plane containing the filaments. Also, the roll 29 is oriented with respect to the primary filaments 16 exactly as were the rolls 24 and 25. Thus the curved portion of the movable member or belt 31 is tangentially in contact with the filaments.

The function of the modified form of the invention is similar to that of the preferred embodiment in that the frictional engagement between the flexible belt 31 and the primary filaments 16 drives the belt and the belt thus serves to maintain the filaments in parallel alignment with one another. Through use of the modified form of the invention, a change in frictional resistance may be readily made by merely substituting belts formed of materials having difierent coefficients of friction thus compensating for different drawing speeds of the primary filaments. The belt 31 may suitably be formed of a thin steel or other metal band having a smooth surface so as to allow the primary filaments to laterally shift relative to one another to bring them into proper alignment. Through use of different metals and thicknesses for the belt, a change may be made in the amount of force required for the filaments to drive the same, thus controlling their ability to laterally shift depending upon desired conditions. This may also be accomplished with the rollers 24 and 25 by changing the diameter or material from which they are formed.

Through use of the present invention, glass fiber mats substantially free of shot and having uniform fiber diameters within a relatively narrow range are produced by maintaining the primary filamentsin parallel, spaced alignment with respect to one another and presenting them for endwise contact with the attenuating blast While thus positioned. Also, use of the instant invention eliminates the necessity of operating personnel keeping a close watch on the process in order to realign filaments and thus a material savings in cost results.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred embodiment of the same, and that various changes may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

What I claim is:

1. In apparatus for forming attenuated glass fibers including means for moving a plurality of spaced aligned glass filaments toward an attenuating means, alignment maintaining means for maintaining said filaments in horizontal alignment comprising a body of revolution in which all surface elements define a straight line, said body having a cross sectional configuration such that all points on the surface of the body which are defined by the intersection of the periphery of the body and a plane passing through the body perpendicular to the axis of revolution are substantially equally spaced from the axis of revolution of said body, and means rotatably supporting the body of revolution in substantially tangential contact with the filaments and with the axis of revolution of said body extending substantially at a right angle to the path of movement of said filaments whereby said filaments rotate said body of revolution.

2. In apparatus for forming attenuated glass fibers including means for moving a plurality of spaced aligned glass filaments toward attenuating means, alignment maintaining means for maintaining the filaments in horizontal alignment along their path of movement comprising a rotatable cylindrical member having a substantially smooth and continuous filament engaging surface, and means for rotatably supporting said member in substantially tangential contact with the filaments with the axis of rotation of said member at substantially a right angle to the path of movement of said filaments whereby said filaments rotate said cylindrical member.

3. In apparatus for forming attenuated glass fibers including means for drawing filaments from a molten body and feeding said filaments in aligned spaced relationship toward an attenuating means, means for maintaining the filaments in horizontal alignment, said alignment maintaining means comprising a movable member having a smooth filament engaging surface defining a straight line and extending transversely at substantially a 90 angle to the direction of movement of the filaments, and means for mounting said member in substantially tangential conby the intersection of a pair of planes the first of which is' substantially parallel to the plane of the filaments and the second of which is oriented to the first at substantially a angle, said body having a substantially smooth and continuous surface configuration such that when in tangential contact with the filaments the points of tangency define a straight line, means supporting the body in substantially tangential contact with the primary filaments whereby said filaments rotate said body, and a back up member adjacent the attenuating blast and having a smooth surface in contact with the filaments to restrain the'filaments against the action of the attenuating blast.

5. In apparatus for forming attenuated glass fibers including means for moving a plurality of spaced aligned glass filaments in a given plane toward attenuating means, alignment maintaining means for maintaining the filaments in horizontal alignment along their path of movement comprising a pair of spaced, rotatable rolls having substantially smooth and continuous filament engaging surfaces and having their axes oriented at substantially a 90 angle to the direction of travel of the filaments and support means for rotatably supporting said rolls on opposite sides of the path of movement of the filaments and in substantially tangential contact with said filaments, whereby said filaments rotate the rolls.

6. Apparatus as defined in claim 5, wherein the rolls are positioned so that the plane of the filaments contains a portion of the surface of each of said rolls.

7. In apparatus for forming attenuated glass fibers including means for continuously moving a plurality of aligned glass filaments along a given path and attenuating means positioned along said path, the improvement which comprises means for maintaining horizontal filament alignment including a movable member engageable with the filaments and having a substantially smooth and continuous filament engaging surface and having a linear surface extending transversely and substantially at a 90 angle to the direction of travel of the filaments, and means supporting said member in substantially tangential contact with the filaments whereby said member is moved by said filaments.

8. Apparatus as defined in claim 7, wherein the movable member comprises an endless belt.

9. Apparatus as defined in claim 8, wherein a back up member is provided and positioned with a surface thereof in contact with the filaments to resist the action of the attenuating means, said surface being substantially smooth.

10. In apparatus for forming attenuated glass fibers including means for moving a plurality of spaced aligned glass filaments in a given plane toward attenuating means, alignment maintaining means for maintaining filaments in horizontal alignment along their path of movement comprising an elongated member having a substantially smooth and continuous curved surface portion in substantially tangential contact with the filaments and mounted for free movement in an arcuate path about an axis, said member being moved by said filaments, said curved surface portion having radii of curvature along the length thereof such that said surface portion when in tangential contact with the filaments defines a straight line along the points of tangential contact, said movable portion having its axis of movement located along a line defined by a pair of planes one of'v'vhich is substantially parallel to the plane containing a plurality of filaments and the other of. which is spaced from the first plane at substantially a 90 angle.

, 11. A method. of maintaining primary glass filaments in horizontal alignment prior to being attenuated into fibers of smaller diameter, comprising drawing primary filamentsv from a supply of molten glass by applying a drawing force thereto while initially aligningthe drawn filaments in substantial parallelism and moving said filaments along a given path of movement, and. maintaining the primary filaments inhorizontal alignment along said path by passing'said filaments in substantially tangential contact with .a rotatable body having a substantially References Cited in the file of this patent UNITED STATES PATENTS 2,489,243 Stalego Nov. 22, 1949 2,571,025 Fletcher Oct. 9, 1951 2,728,699 Labino Dec. 27, 1955 2,990236 Riseley June 27, 1961 

